Perylene diimide derivative-based flexible fluorescence sensor for benzene series steam detection

Abstract

The invention relates to a perylene diimide derivative-based flexible fluorescent sensor for benzene vapor detection, and belongs to the technical field of fluorescent sensors, in the flexible fluorescent sensor, a perylene diimide derivative is used as a fluorescent probe, and the perylene diimide derivative is HO-PDI-OH or UPy-PDI-UPy; the method comprises the following steps: doping a fluorescent probe HO-PDI-OH or UPy-PDI-UPy into a polyurethane matrix, so as to obtain the flexible fluorescent sensor. The flexible fluorescent sensor prepared by the invention can realize specific detection of benzene steam, can be used for detecting benzene steam, can be recognized by naked eyes through light-emitting color change, and is good in portability, high in sensitivity, quick in response and easy to operate.

Description

Technical Field

[0001] The invention belongs to the technical field of fluorescent sensors, and in particular relates to a flexible fluorescent sensor based on perylene diimide derivatives for detecting benzene vapor. Background Art

[0002] Against the backdrop of the rapid development of the global manufacturing industry, the industrialization process has been accelerated with the assistance of artificial intelligence, resulting in an increase in the use of benzene as a basic chemical raw material year by year. However, benzene poses a potential threat to human health and the environment due to its volatility and biological toxicity, and its emissions and leakage have caused global concerns about the living environment and public health. Therefore, it is particularly important to develop efficient, sensitive and accurate benzene detection methods to monitor the concentration of benzene in the environment and ensure public safety. Although traditional detection methods such as gas chromatography and liquid chromatography have high accuracy, they often require complex sample pretreatment and expensive equipment, which limits their practical application.

[0003] Organic fluorescent sensors can be used to monitor benzene in the air and water, helping to track pollution sources and assess environmental quality. In industrial production, especially in the petrochemical and coating industries, organic fluorescent sensors can detect the concentration of benzene in real time, prevent leaks and accidents, and usually have high sensitivity. Organic small molecule fluorescent sensors have the advantages of high sensitivity and real-time detection, but these small molecule materials are mostly used for detection in solutions, and the portability of vapor detection is poor. They are mostly manifested as changes in fluorescence intensity, making it difficult to achieve naked eye recognition of benzene vapor. Summary of the invention

[0004] The purpose of the present invention is to provide a perylene diimide derivative-based flexible fluorescent sensor for detecting benzene series vapor. Two fluorescent probes based on perylene diimide derivatives are synthesized, and a polyurethane-based flexible fluorescent sensor based on the fluorescent probe is prepared. The sensor is used to detect benzene series vapor, and has the characteristics of luminescent color change, visual recognition, good portability, high sensitivity, rapid response, and easy operation, and has potential application prospects in the field of benzene series detection.

[0005] Technical problem to be solved by the present invention: Organic small molecule fluorescent sensors have the advantages of high sensitivity and real-time detection, but these small molecule materials are mostly used for detection in solutions, have poor portability in vapor detection, and are mostly manifested as changes in fluorescence intensity, making it difficult to achieve naked eye identification of benzene vapor.

[0006] The purpose of the present invention can be achieved through the following technical solutions: A perylene diimide derivative-based flexible fluorescent sensor for detecting benzene vapor, wherein the perylene diimide derivative is a fluorescent probe, and the structure of the perylene diimide derivative is shown in formula (I): Formula (I); In the formula (I), R is hydroxy, a hydroxy derivative, 2-ureido-6-methylpyrimidin-4(1H)-one or a 2-ureido-6-methylpyrimidin-4(1H)-one derivative.

[0007] When R is a hydroxyl group or a hydroxyl derivative, the perylene diimide derivative is HO-PDI-OH.

[0008] When R is 2-ureido-6-methylpyrimidin-4(1H)-one or a derivative thereof, the perylene diimide derivative is UPy-PDI-UPy.

[0009] Furthermore, the structure of HO-PDI-OH is shown in formula (II): Formula (II).

[0010] Furthermore, the preparation method of HO-PDI-OH comprises the following steps: Under nitrogen protection, 1-amino-3,6,9-trioxa-11-undecanol, 3,4,9,10-perylenetetracarboxylic dianhydride and triethylamine were dissolved in organic solvent 1 to react to obtain brown solid HO-PDI-OH.

[0011] Furthermore, the organic solvent 1 includes at least one of N,N-dimethylformamide and dimethyl sulfoxide.

[0012] Furthermore, the reaction temperature is 140-160°C, and the reaction time is 3-5h.

[0013] Furthermore, the molar ratio of 1-amino-3,6,9-trioxa-11-undecanol, 3,4,9,10-perylenetetracarboxylic dianhydride and triethylamine is (2-3):(1-2):(32-39).

[0014] Furthermore, the usage ratio of the 1-amino-3,6,9-trioxa-11-undecanol and the organic solvent 1 is (3-4) mmol: (10-12) mL.

[0015] Further, the synthetic route of HO-PDI-OH is as follows: .

[0016] Furthermore, the structure of UPy-PDI-UPy is shown in formula (III): Formula (III).

[0017] Furthermore, the preparation method of UPy-PDI-UPy comprises the following steps: A1. Dissolve 2-amino-6-methylpyrimidin-4(1H)-one and N,N-carbonyldiimidazole in N,N-dimethylformamide (DMF) to obtain UPy-Imidazole. Then, dissolve UPy-Imidazole and ethanolamine in tetrahydrofuran (THF) to obtain UPy-OH. Finally, dissolve UPy-OH in hexamethylene diisocyanate to obtain the target product UPy-NCO. A2. Under nitrogen protection, 1-amino-3,6,9-trioxa-11-undecanol, 3,4,9,10-perylenetetracarboxylic dianhydride (PDI) and triethylamine are dissolved in organic solvent 1 to react to obtain brown solid HO-PDI-OH; A3. Under nitrogen protection, HO-PDI-OH, UPy-NCO and dibutyltin dilaurate (DBTDL) were dissolved in organic solvent 2 to react to obtain brown solid UPy-PDI-UPy.

[0018] Furthermore, in step A3, the organic solvent 2 includes at least one of N,N-dimethylformamide and dimethyl sulfoxide.

[0019] Furthermore, in step A3, the reaction temperature is 60-80°C and the reaction time is 2-3h.

[0020] Furthermore, in step A3, the usage ratio of HO-PDI-OH, UPy-NCO and organic solvent 2 is (1-2) mmol: (3-5) mmol: (40-50) mL.

[0021] Further, the synthetic route of UPy-PDI-UPy is as follows:

[0022] The preparation method of a perylene diimide derivative-based flexible fluorescent sensor for detecting benzene vapor comprises the following steps: Step 1, adding polytetrahydrofuran, 1,6-diisocyanate hexane and dibutyltin dilaurate to dry tetrahydrofuran to obtain a mixture, stirring the mixture under nitrogen protection, cooling the mixture to room temperature after the reaction, adding n-hexane thereto, collecting the precipitate, washing and drying, and obtaining a blank polyurethane matrix; Step 2: Mix a blank polyurethane matrix with a perylene diimide derivative, add tetrahydrofuran, and heat until completely dissolved. Pour the solution into a polytetrafluoroethylene mold, let it stand overnight at room temperature, and vacuum dry to obtain a flexible fluorescent sensor.

[0023] Furthermore, in step 2, the mass ratio of the perylene diimide derivative to the polyurethane matrix is ​​(0.010-0.020):3.

[0024] Further, the specific reaction route of the polyurethane matrix is ​​as follows:

[0025] Specifically, the two fluorescent probes provided by the present invention gradually red-shift their fluorescence colors as their concentration increases in solution, achieving a transition from a monomer to an excimer or even an aggregate. In a powder state, both probes produced fluorescence responses to petroleum ether, benzene, dichloromethane, toluene, and xylene solvent vapors, with HO-PDI-OH mainly showing an increase in fluorescence intensity, and UPy-PDI-UPy mainly showing a blue shift in fluorescence wavelength. Among them, benzene vapor makes the fluorescence blue shift effect most obvious, and the specific recognition of benzene vapor is achieved by the transition from orange-red light to orange-yellow light.

[0026] From its fluorescence spectrum, it can be seen that the existence forms of HO-PDI-OH molecules in the sensor based on HO-PDI-OH fluorescent probe include aggregated state, excimer and monomeric form. Compared with the powder state, the aggregation degree of the probe molecules has decreased, indicating that the polyurethane matrix can effectively regulate the aggregation state of the probe molecules, and the spatial confinement effect provided by it can improve the dispersion degree of the molecules. The sensor was placed in benzene, toluene, xylene, chloroform, and petroleum ether vapors, respectively. The solvent molecules can increase the distance between the probe molecules and reduce the aggregation of the probe molecules. From petroleum ether to benzene, the luminescent color of the sensor gradually changes from orange-red to yellow, realizing the specific detection of benzene. After fumigation in benzene vapor for different lengths, the fluorescence spectrum changes were characterized, showing that the process of benzene molecules penetrating into the polyurethane matrix and dissociating the fluorescent probe HO-PDI-OH aggregates can reach equilibrium in a relatively short time, verifying the fast detection characteristics of the sensor.

[0027] In the sensor based on UPy-PDI-UPy fluorescent probe, the existence forms of the fluorescent probe UPy-PDI-UPy mainly include monomers, excimers and aggregates, and the proportion of aggregates is significantly lower than that of the probe HO-PDI-OH in the sensor. The sensor containing the fluorescent probe UPy-PDI-UPy was fumigated with petroleum ether, dichloromethane, xylene, toluene and benzene vapors. Except that the spectrum remained basically stable under the action of petroleum ether vapor, the other solvents showed the ability to dissociate the molecular aggregates of the fluorescent probe UPy-PDI-UPy. The change in luminescent color can also be clearly observed from the fluorescent photos of the sensor. The luminescence of the sensor gradually transitioned from the orange-yellow in the initial state to bright yellow and yellow-green, and showed bright green luminescence in benzene vapor, showing obvious specific recognition of benzene vapor. Compared with the sensor based on HO-PDI-OH, the detection recognition is higher, the recognition effect is more obvious, and the response speed is faster.

[0028] Beneficial effects of the present invention: In the technical solution of the present invention, two probe molecules HO-PDI-OH and UPy-PDI-UPy are physically doped into the polyurethane matrix respectively, and the spatial confinement effect provided by the polyurethane polymer chain and the probe molecule end group is utilized. The prepared flexible fluorescent sensor shows that the luminescence intensity of the aggregate is significantly reduced under the action of solvent vapor, and the luminescence color of the fluorescent sensor gradually blue-shifts in the order of petroleum ether, dichloromethane, xylene, toluene, and benzene, thereby realizing the specific detection of benzene vapor. Among them, the sensor based on UPy-PDI-UPy has a higher degree of recognition of the luminescence color change and a shorter response time. The flexible fluorescent sensor of the present invention is used to detect benzene vapor, which has the characteristics of luminescence color change, naked eye recognition, good portability, high sensitivity, rapid response and easy operation, and has potential application prospects in the field of benzene detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 The fluorescence spectra of HO-PDI-OH prepared in Example 1 at different concentrations in dichloromethane solution; Figure 2 The curve showing the relationship between the fluorescence intensity ratio of the HO-PDI-OH excimer complex and the monomer luminescence and the solution concentration prepared in Example 1; Figure 3 The fluorescence spectra of UPy-PDI-UPy prepared in Example 2 at different concentrations in dichloromethane solution; Figure 4 The curve showing the relationship between the fluorescence intensity ratio of the UPy-PDI-UPy excimer complex and the monomer luminescence and the solution concentration prepared in Example 2; Figure 5 The fluorescence spectra of HO-PDI-OH prepared in Example 1 fumigated with different solvent vapors; Figure 6 The corresponding photographs of HO-PDI-OH prepared in Example 1 after being fumigated with different solvent vapors under fluorescent light and ultraviolet light; Figure 7 The fluorescence spectra of UPy-PDI-UPy prepared in Example 2 after fumigation with different solvent vapors; Figure 8 The corresponding photographs of UPy-PDI-UPy prepared in Example 2 after being fumigated with different solvent vapors under fluorescent light and ultraviolet light; Fig. 9 The fluorescence spectra of the flexible fluorescent sensor S1 prepared in Example 3 under the fumigation of different solvents; Fig.10 Fluorescence photos of the flexible fluorescent sensor S1 prepared in Example 3 under the fumigation of different solvents; Fig.11The fluorescence spectra of the flexible fluorescent sensor S1 prepared in Example 3 at different times under the action of benzene solvent fumigation; Fig.12 The fluorescence spectra of the flexible fluorescent sensor S2 prepared in Example 4 under the fumigation of different solvents; Fig.13 Fluorescence photos of the flexible fluorescent sensor S2 prepared in Example 4 under the fumigation of different solvents; Fig.14 The fluorescence spectra of the flexible fluorescent sensor S2 prepared in Example 4 at different times under the fumigation of benzene solvent. DETAILED DESCRIPTION

[0030] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] Example 1: This example provides a method for preparing HO-PDI-OH, comprising the following steps: Under nitrogen protection, 1-amino-3,6,9-trioxa-11-undecanol (2.6 g, 13.5 mmol), 3,4,9,10-perylenetetracarboxylic dianhydride (2.2 g, 5.6 mmol) and triethylamine (25 mL, 180 mmol) were dissolved in dry DMSO (50 mL) to obtain a mixture. The mixture was stirred at 150 ° C for 4 h and then cooled to 80 ° C. Then, a mixture of 10% hydrochloric acid (600 mL) and methanol (300 mL) was added to the reaction solution, and the mixture was stirred at 60 ° C for 2 h, cooled to room temperature and allowed to stand for a long time, and filtered. The filter residue was dissolved in chloroform, washed with deionized water, dried over anhydrous magnesium sulfate, and filtered. The solvent was evaporated under reduced pressure, and the crude product was purified by column chromatography (stationary phase: neutral alumina; eluent: dichloromethane / methanol = 5 / 1) and then recrystallized from n-hexane to obtain 3.6 g of brown solid HO-PDI-OH with a yield of 86%. Its H NMR spectrum data are as follows 1 HNMR (400 MHz, DMSO-d 6 ): δ7.59(t,J=10.7Hz,8H),4.59(t,J=5.5Hz,2H),3.77-3.39(m,32H).

[0032] like Figure 1 , Figure 2As shown in the figure, in a dichloromethane solution, the fluorescent probe HO-PDI-OH changes from a monomer to an exciplex as the concentration increases, and the emission color changes from (yellow) green to yellow, proving that in a low-concentration solution the probe exists mainly in the form of a single molecule, while in a high-concentration solution it exists in the form of an exciplex or even a multi-molecular aggregate. Figure 5 , 6 As shown, after the probe HO-PDI-OH powder was fumigated with solvent vapor, the fluorescence intensity increased in the order of petroleum ether (PE), benzene (BZ), dichloromethane (MC), toluene (TL) to xylene (XY), while the spectral wavelength remained basically unchanged, indicating that the probe HO-PDI-OH powder can detect benzene vapor by changing the luminescence intensity.

[0033] Example 2: This example provides a method for preparing UPy-PDI-UPy, comprising the following steps: 2-Amino-6-methylpyrimidin-4(1H)-one (6g, 0.048mol) and N,N'-carbonyldiimidazole (9.4g, 0.058mol) were dissolved in DMF (110mL) and reacted at 90°C for 5 hours under nitrogen protection. After the reaction was completed, it was cooled to room temperature, 150mL of acetone was added to the system as a precipitant, and it was allowed to stand for 2 hours. The filter residue was washed with acetone and dried in a vacuum oven at 50°C to obtain the target product Upy-Imidazole, which was 7.8g of white solid with a yield of 74.1%, and was directly used in the subsequent steps.

[0034] UPy-Imidazole (6 g, 0.027 mol) and ethanolamine (2.5 g, 0.041 mol) were dissolved in THF (120 mL) and reacted at 25 °C for 3 hours under nitrogen atmosphere. After the reaction, the reaction solution was concentrated, 400 mL of distilled water was added to the system as a precipitant, and the mixture was allowed to stand for half an hour. The residue was filtered and washed with deionized water and acetone in turn, and dried in a vacuum oven at 50 °C to obtain the target product UPy-OH.

[0035] UPy-OH (1.5 g, 7 mmol) was dissolved in 1,6-diisocyanate (HDI) (15 mL), heated to 90 °C under nitrogen atmosphere, reacted for 24 hours, cooled to room temperature after the reaction, added 100 mL of ethyl acetate as a precipitant to the system, allowed to stand for half an hour, filtered, and the residue was washed with toluene and acetone in turn. Placed in a vacuum oven at 50 °C and dried to obtain the target product UPy-NCO.

[0036] Under nitrogen protection, the fluorescent probe HO-PDI-OH (1.00 g, 1.3 mmol), UPy-NCO (1.28 g, 3.25 mmol) and DBTDL (83 μL) were dissolved in DMF (40 mL) to obtain a mixture, which was heated to 70°C for 2 h. The residue was filtered and recrystallized from chloroform / n-hexane to obtain 1.76 g of brown solid UPy-PDI-UPy with a yield of 90%. Its H NMR spectrum data are as follows: 1 HNMR (400MHz, CDCl 3 ): δ13.12(s,2H),12.90(s,2H),11.75(s,2H),10.24(s,1H),10.10(s,1H),8.68-8.41(m, 8H),5.83(s,2H),4.51-4.43(m,4H),3.95-3.55(m,36H),2.23(s,6H),0.94-0.83(m,16H).

[0037] like Figure 3 , Figure 4 As shown in the figure, the fluorescent probe UPy-PDI-UPy in dichloromethane solution changes from monomer to exciplex as the concentration increases. The emission color changes from (yellow) green to yellow, proving that the probe exists mainly in the form of a single molecule in low-concentration solutions, and in the form of an exciplex or even a multi-molecular aggregate in high-concentration solutions. Figure 7 , Figure 8 As shown in the figure, under the action of solvent vapor, the luminescence wavelength of the UPy-PDI-UPy powder undergoes a relatively obvious blue shift in the order of petroleum ether, dichloromethane, toluene, xylene to benzene. The powder after benzene vapor fumigation has the highest luminescence intensity and the most obvious blue shift in luminescence wavelength, showing obvious specific recognition of benzene vapor. It can also be clearly seen from the fluorescence photos of the samples that the luminescence color of the samples after benzene vapor fumigation turns orange-yellow, which is obviously different from the samples after other solvent vapor fumigation, achieving specific recognition of benzene.

[0038] Embodiment 3: This embodiment provides a method for preparing a flexible fluorescent sensor S1, comprising the following steps: Step 1. Add polytetrahydrofuran (Mn=650, 1.95 g, 3 mmol), DBTDL (30 μL) and HDI (0.5 mL, 3.02 mmol) to dry tetrahydrofuran (10 mL) to obtain a mixture. Under nitrogen protection, the mixture was stirred and reacted at 60°C for 20 hours. After cooling to room temperature, n-hexane (200 mL) was added thereto as a precipitant, the precipitate was collected, washed with n-hexane, and vacuum dried to obtain a blank polyurethane matrix (PU); Step 2: Mix the polyurethane matrix (3.0 g) with the fluorescent probe HO-PDI-OH (0.015 g) prepared in Example 1, add tetrahydrofuran (3 mL), and heat until completely dissolved. Pour the solution into a polytetrafluoroethylene mold (3.0 × 1.0 × 0.2 cm 3 ) and allowed to stand overnight at room temperature to allow the solvent to evaporate slowly. The obtained sample was then vacuum dried for 24 hours to obtain a flexible fluorescent sensor S1.

[0039] like Fig. 9 As shown in the figure, the fluorescent probe HO-PDI-OH is loaded into the polyurethane matrix. The emission peak of sensor S1 is located at 645nm, and there are two shoulder peaks located at 589 and 548nm, respectively. This shows that the existence forms of the probe HO-PDI-OH molecules include aggregation, excimer and monomer. The polyurethane matrix can effectively regulate the aggregation state of the probe molecules, and the spatial confinement effect it provides can improve the dispersion of the molecules. Fig.10 As shown in the figure, from petroleum ether to benzene, the luminescent color of S1 gradually changes from orange-red to yellow, achieving specific detection of benzene. Fig.11 As shown, the fluorescence spectrum changes after fumigation in benzene vapor for different lengths of time show that the fluorescence spectrum reaches equilibrium in a relatively short time, verifying the quick detection characteristics of the sensor.

[0040] Example 4: The example provides a method for preparing a flexible fluorescent sensor S2, comprising the following steps: Step 1. Add polytetrahydrofuran (Mn=650, 1.95 g, 3 mmol), DBTDL (30 μL) and HDI (0.5 mL, 3.02 mmol) to dry tetrahydrofuran (10 mL) to obtain a mixture. Under nitrogen protection, the mixture was stirred and reacted at 60°C for 20 hours. After cooling to room temperature, n-hexane (200 mL) was added thereto as a precipitant, the precipitate was collected, washed with n-hexane, and vacuum dried to obtain a blank polyurethane matrix (PU); Step 2: Mix the polyurethane matrix (3.0 g) with the fluorescent probe UPy-PDI-UPy (0.015 g) prepared in Example 2, add tetrahydrofuran (3 mL), and heat until completely dissolved. Pour the solution into a polytetrafluoroethylene mold (3.0 × 1.0 × 0.2 cm 3 ) and allowed to stand overnight at room temperature to allow the solvent to evaporate slowly. The obtained sample was then vacuum dried for 24 hours to obtain a flexible fluorescent sensor S2.

[0041] like Fig.12As shown in Figure 2, the existence forms of the fluorescent probe UPy-PDI-UPy in S2 mainly include monomers, excimer complexes and aggregates. Compared with sensor S1, the relative intensity of the emission peak of the fluorescent probe monomer in S2 is significantly enhanced, and the relative intensity of the emission peak of the aggregate is significantly weakened. Fig.13 As shown in the figure, under the action of solvent vapor, the change of luminescent color can be clearly observed from the fluorescence photos of the sensor. The luminescence of sensor S2 gradually changes from the initial orange-yellow to bright yellow and yellow-green, and presents bright green luminescence in benzene vapor, showing obvious specific recognition of benzene vapor. For detection, the recognition is higher and the recognition effect is more obvious. Fig.14 As shown, through the time-dependent fluorescence spectrum, it can be found that the fluorescence spectrum of sensor S2 under the action of benzene vapor basically reaches equilibrium after 3 minutes, and the detection speed is faster.

[0042] In the description of the specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0043] The above contents are merely examples and explanations of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the invention or exceed the scope defined by the claims, they shall all fall within the protection scope of the present invention.

Claims

1. A flexible fluorescent sensor based on perylene diimide derivatives for detecting benzene vapor, characterized in that: The method for preparing the flexible fluorescent sensor comprises the following steps: Step 1, adding polytetrahydrofuran, 1,6-diisocyanate hexane and dibutyltin dilaurate to dry tetrahydrofuran to obtain a mixture, stirring the mixture under nitrogen protection, cooling the mixture to room temperature after the reaction, adding n-hexane thereto, collecting the precipitate, washing and drying, and obtaining a blank polyurethane matrix; Step 2: Mix a blank polyurethane matrix with a perylene diimide derivative, add tetrahydrofuran, and heat until completely dissolved. Pour the solution into a polytetrafluoroethylene mold, let stand overnight at room temperature, and vacuum dry to obtain a flexible fluorescent sensor. The structure of the perylene diimide derivative is shown in formula (I): Formula (I); In the formula (I), R is hydroxy, a hydroxy derivative, 2-ureido-6-methylpyrimidin-4(1H)-one or a 2-ureido-6-methylpyrimidin-4(1H)-one derivative.

2. The perylene diimide derivative-based flexible fluorescent sensor for detecting benzene vapor according to claim 1, characterized in that: When R in the structural formula of the perylene diimide derivative is a hydroxyl group or a hydroxyl derivative, the perylene diimide derivative is HO-PDI-OH, and the structure is shown in formula (II): Formula (II).

3. The perylene diimide derivative-based flexible fluorescent sensor for detecting benzene vapor according to claim 1, characterized in that: When R in the structural formula of the perylene diimide derivative is 2-ureido-6-methylpyrimidin-4(1H)-one or a derivative thereof, the perylene diimide derivative is UPy-PDI-UPy, and the structure is shown in formula (III): Formula (III).

4. The perylene diimide derivative-based flexible fluorescent sensor for detecting benzene vapor according to claim 2, characterized in that: The preparation method of HO-PDI-OH comprises the following steps: Under nitrogen protection, 1-amino-3,6,9-trioxa-11-undecanol, 3,4,9,10-perylenetetracarboxylic dianhydride and triethylamine were dissolved in organic solvent 1 to react to obtain brown solid HO-PDI-OH.

5. The perylene diimide derivative-based flexible fluorescent sensor for detecting benzene vapor according to claim 3, characterized in that: The preparation method of UPy-PDI-UPy comprises the following steps: A1, dissolving 2-amino-6-methylpyrimidin-4(1H)-one and N,N-carbonyldiimidazole in N,N-dimethylformamide to obtain UPy-Imidazole, then dissolving UPy-Imidazole and ethanolamine in tetrahydrofuran to obtain UPy-OH, and finally dissolving UPy-OH in hexamethylene diisocyanate to obtain the target product UPy-NCO; A2, under nitrogen protection, 1-amino-3,6,9-trioxa-11-undecanol, 3,4,9,10-perylenetetracarboxylic dianhydride and triethylamine were dissolved in organic solvent 1 to react to obtain brown solid HO-PDI-OH; A3. Under nitrogen protection, HO-PDI-OH, UPy-NCO and dibutyltin dilaurate were dissolved in organic solvent 2 to react to obtain brown solid UPy-PDI-UPy.

6. The perylene diimide derivative-based flexible fluorescent sensor for detecting benzene vapor according to claim 4, characterized in that: The organic solvent 1 includes at least one of N,N-dimethylformamide and dimethyl sulfoxide; the reaction temperature is 140-160° C., and the reaction time is 3-5 hours.

7. The perylene diimide derivative-based flexible fluorescent sensor for detecting benzene vapor according to claim 4, characterized in that: The molar ratio of the 1-amino-3,6,9-trioxa-11-undecanol, 3,4,9,10-perylenetetracarboxylic dianhydride and triethylamine is (2-3):(1-2):(32-39); the amount ratio of the 1-amino-3,6,9-trioxa-11-undecanol and the organic solvent 1 is (3-4) mmol:(10-12) mL.

8. The perylene diimide derivative-based flexible fluorescent sensor for detecting benzene vapor according to claim 5, characterized in that: In the step A3, the organic solvent 2 includes at least one of N,N-dimethylformamide and dimethyl sulfoxide, the reaction temperature is 60-80° C., and the reaction time is 2-3 hours.

9. The perylene diimide derivative-based flexible fluorescent sensor for detecting benzene vapor according to claim 5, characterized in that: In the step A3, the usage ratio of HO-PDI-OH, UPy-NCO and organic solvent 2 is (1-2) mmol: (3-5) mmol: (40-50) mL.

10. The perylene diimide derivative-based flexible fluorescent sensor for detecting benzene vapor according to claim 1, characterized in that: The mass ratio of the perylene diimide derivative to the polyurethane matrix is ​​(0.010-0.020):3.

Images